Introduction
In this article I will explain how to find a substring from a string and if present then reverse the substring. Basically it is a frequently asked interview question. I have encountered this question many times in interviews. That is why I decided to write this article.
Now use the following procedure to implement it.
Step 1
First of all you have to create a new Windows Store Application, as in:
- Open Visual Studio 2012
- "File" -> "New" -> "Project..."
- Choose "Template" -> "Visual C#" -> "Window Store app"
- Choose "Blank App (XAML)" then rename the application
![new-windows-store-app.jpg]()
Step 2
Write the following XAML code in "Mainpage.Xaml" (that is available in Solution Explorer):
<Page
x:Class="number_app.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:number_app"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">
<Grid Background="Red">
<Grid.RowDefinitions>
<RowDefinition Height="116*"/>
<RowDefinition Height="60*"/>
<RowDefinition Height="52*"/>
<RowDefinition Height="48*"/>
<RowDefinition Height="40*"/>
<RowDefinition Height="53*"/>
<RowDefinition Height="310*"/>
<RowDefinition Height="89*"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="328*"/>
<ColumnDefinition Width="353*"/>
<ColumnDefinition Width="685*"/>
</Grid.ColumnDefinitions>
<TextBlock Text="Enter string :" FontSize="20" FontWeight="ExtraBold" FontFamily="Arial" Grid.Column="1" Grid.Row="2" ></TextBlock>
<TextBox x:Name="textbox1" Grid.Column="2" Grid.Row="2" Width="200" Height="32" HorizontalAlignment="Left" VerticalAlignment="Top"></TextBox>
<TextBlock Text="Enter string :" FontSize="20" FontWeight="ExtraBold" FontFamily="Arial" Grid.Column="1" Grid.Row="2" ></TextBlock>
<TextBlock Text="Enter substring for Reverse :" FontSize="20" FontWeight="ExtraBold" FontFamily="Arial" Grid.Column="1" Grid.Row="3" ></TextBlock>
<TextBox x:Name="textbox2" Grid.Column="2" Grid.Row="3" Width="200" Height="32" HorizontalAlignment="Left" VerticalAlignment="Top"></TextBox>
<Button x:Name="button1" Content="click" Grid.Column="2" Grid.Row="4" Width="104" Click="button1_Click" Background="Yellow" Foreground="Black" Height="38" Margin="0,3,0,0" Grid.RowSpan="2" VerticalAlignment="Top" />
<TextBlock x:Name="text1" FontSize="20" FontWeight="ExtraBold" FontFamily="Arial" Grid.Column="2" Grid.Row="5" Width="619" HorizontalAlignment="Left" ></TextBlock>
</Grid>
</Page>
Step 3
Now write the following C# code for the button within "Mainpage.Xaml.cs".
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;
using System.Text;
namespace number_app
{
public sealed partial class MainPage : Page
{
public MainPage()
{
this.InitializeComponent();
}
protected override void OnNavigatedTo(NavigationEventArgs e)
{
}
public void number(string str)
{
bool b= str.Contains(substr);
string temp = "";
if (b == true)
{
for (int i = substr.Length - 1; i >= 0; i--)
{
temp += substr[i];
}
str = str.Replace(substr, temp);
text1.Text = str;
}
else
{
text1.Text = "substring " + substr + " not found";
}
}
string str;
string substr;
private void button1_Click(object sender, RoutedEventArgs e)
{
str = null;
substr = null;
str = textbox1.Text;
substr = textbox2.Text;
number(str);
}
}
}
Step 4
Now Run your app.
![run-string-app.jpg]()
![substring-not-found.jpg]()
![output-of-string-app.jpg]()